On Fri, Jun 10, 2016 at 09:55:17PM +0200, Tomasz Nowicki wrote:
> To enable PCI legacy IRQs on platforms booting with ACPI, arch code
> should include ACPI specific callbacks that parse and set-up the
> device IRQ number, equivalent to the DT boot path. Owing to the current
> ACPI core scan handlers implementation, ACPI PCI legacy IRQs bindings
> cannot be parsed at device add time, since that would trigger ACPI scan
> handlers ordering issues depending on how the ACPI tables are defined.
Uh, OK :) I can't figure out exactly what the problem is here -- I
don't know where to look if I wanted to fix the scan handler ordering
issues, and I don't know how I could tell if it would ever be safe to
move this from driver probe-time back to device add-time.
I also notice that x86 and ia64 call acpi_pci_irq_enable() even later,
when the driver *enables* the device. Is there a reason you didn't do
it at the same time as x86 and ia64? This is another of those pcibios
hooks that really don't do anything arch-specific, so I can imagine
refactoring this somehow, someday.
Did we have this conversation before? It seems vaguely familiar, so I
apologize if you already explained this once.
> To solve this problem and consolidate FW PCI legacy IRQs parsing in
> one single pcibios callback (pending final removal), this patch moves
> DT PCI IRQ parsing to the pcibios_alloc_irq() callback (called by
> PCI core code at device probe time) and adds ACPI PCI legacy IRQs
> parsing to the same callback too, so that FW PCI legacy IRQs parsing
> is confined in one single arch callback that can be easily removed
> when code parsing PCI legacy IRQs is consolidated and moved to core
> PCI code.
>
> Signed-off-by: Tomasz Nowicki <tn@xxxxxxxxxxxx>
> Suggested-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> ---
> arch/arm64/kernel/pci.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index d5d3d26..b3b8a2c 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -51,11 +51,16 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
> }
>
> /*
> - * Try to assign the IRQ number from DT when adding a new device
> + * Try to assign the IRQ number when probing a new device
> */
> -int pcibios_add_device(struct pci_dev *dev)
> +int pcibios_alloc_irq(struct pci_dev *dev)
> {
> - dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> + if (acpi_disabled)
> + dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
> +#ifdef CONFIG_ACPI
> + else
> + return acpi_pci_irq_enable(dev);
> +#endif
>
> return 0;
> }
> --
> 1.9.1
>
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